Wire plus laser AM & Hybrid wire plus arc AM Gonçalo Pardal 31-05-2018

Outline: Wire plus laser AM Hybrid wire plus arc AM Goal and objectives Introduction Experimental setup Results WLAAM multi layer sample Conclusions Hybrid wire plus arc AM Goal and objectives Introduction Experimental setup Results Hybrid laser-CMT bead on plate deposition Hybrid laser-CMT WAAM deposition Conclusions

Wire plus laser AM Goal and objectives: Goal: Investigate if WLAM (Wire plus Laser Additive Manufacturing) can produce final shape components. Objectives: Develop a deposition setup. Study single and multi layer deposition. Build AM walls to test the conditions.

Introduction WAAM - Wire and Arc Additive Manufacturing AM technique being researched at Cranfield University for the past 10 years. It uses common welding techniques (MIG, plasma welding) and wire as feedstock. Deposited layers Welding wire Wire feeder Substrate Plasma welding torch Welding arc

Introduction WAAM - Wire and Arc Additive manufacturing The parts are built layer by layer and net shape is achieved. This need to be machined to achieve the final component (between 0.5 mm to 2 mm). Deposition rate in Ti between 400 g/h to 1.2 Kg/h WAAM can be used to build complex metallic parts.

Introduction WLAM: Wire and Laser Additive Manufacturing As a complementary AM technique WLAM was investigated. LASER: Flexibility in beam manipulation Small and controlable beam diameter Higher processing speeds Laser beam Substrate Wire Weld pool WLAAM Wall

Experimental set-up SPI Fibre laser of 3 kW Ar inert atmosphere Wire diamter 0.6 mm Laser head Flexible Argon enclosure Linear stages

Final shape deposition WLAM multi layer sample Final shape deposition Deposition rates are complimentary to WAAM (200 g/h to 400g/h). Layer heights are up 10 times smaller than WAAM. Low surface waviness no finishing machining needed (final shape obtained).

Conclusions WLAM is a viable process to build AM components. It can build very small components in final shape condition, avoiding extra steps to finish the part. The high focus ability of laser generates small weld pools making the wire feeding a very important factor.

Hybrid wire plus arc AM Goal: Investigate how laser in conduction mode can be used to stabilize MIG WAAM deposition and increase the deposition rate of Ti-6Al-4V parts. Objectives: Use a defocused high power laser to stabilize and/or modify the weld bead shape of MIG Ti-6Al- 4V deposition. Increase the deposition rate of Ti-6Al-4V when compared PTA (Plasma Transferred Arc) WAAM deposition.

Introduction Ti WAAM: MIG AM wall: Plasma AM wall

Experimental setup – Hybrid laser-CMT bead on plate deposition head Ti-6Al-4V Welding wire MIG welding torch Trailing shield Laser beam Bead on plate weld The wire feed speed was fixed at 9 m/min and the laser power was varied

Results – Hybrid laser-CMT bead on plate deposition Hybrid laser-CMT roots the cathode spot, stopping the arc wandering. This translates to better control in the deposition and better 3D printed parts.

Results – Hybrid laser-CMT bead on plate deposition Hybrid laser reduces the wandering of the arc and the weld bead waviness. Laser increases the deposition rate of the process form 1.5 kg/h to 2.0 kg/h (33% increase). Hybrid laser-CMT increases the deposition rate of Ti by 66.6% when compared to plasma deposition process.

Results – Hybrid laser-CMT WAAM deposition Effective wall width of 2.98 mm (CMT) vs 5.93 mm (Hybrid laser-CMT), increasing the effective deposition. Average layer height decreases, introducing better resolution to the hybrid laser-CMT WAAM process. CMT microstructure more equiaxed when compared to the hybrid process (Higher heat input). Sample 25 CMT WFS/TS = 18 Sample 26 Hybrid laser-CMT WFS/TS = 18 Laser Power = 2500 W

Conclusions Hybrid laser-CMT can stabilize the arc wandering phenomenon and change the typical weld bead shape of with Ti CMT deposition. It can generate straight single bead and wall depositions. Hybrid laser CMT can increase the Ti deposition rate to 2 kg/h, increasing also the WAAM process efficiency without sacrificing its resolution.

NEWAM Building in the research presented here Cranfield won a new Wire based AM programme grant. EPSRC Programme grant ~£6M + £3M industry support = £9M Programme duration 5 years Programme start date June 25th 2018 Main goal: To develop new innovative high build rate metal wire AM processes and systems for net shape deposition at low cost over large volumes with homogeneous microstructure and properties – target 8kg/hr net shape for Ti.

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